Injection molding systems comprise an injection molding machine having a barrel and a screw (or ram) housed within a barrel which injects a fluid material from an exit port of the barrel at a preselected velocity or profile of velocities over an injection cycle into a flow channel or system of channels in a distribution manifold which, in turn, direct the fluid to one or more injection ports which lead to one or more cavities of one or more molds.
Apparati have been developed for controlling the rate of flow of fluid material at a location within a flow channel, bore or nozzle having a straight axis that is aligned with the center of the gate of the mold cavity and along which a valve pin or other mechanical flow controlling mechanism is aligned for purposes of controlling material flow at the gate or at a position immediately upstream of the gate along the axis aligned with the gate. Such systems typically use an actuator mechanism that is aligned with the axis that intersects the gate.